Reducing Error in a Qubit Array

For quite some time, scientists have been thinking about how to create a quantum computer, which uses quantum mechanics to perform operations not possible with modern, classical computers. Quantum mechanical systems are very sensitive to interference though and that has been slowing their development. Researchers at the University of California, Santa Barbara however have designed an array of quantum bits, or qubits that should have an error-rate of less than 1%.

The key to quantum computing is that the particles that store information exist in a superposition; a phenomenon that allows one particle to exist in multiple, mutually-exclusive states at the same time. If a superposition is observed or interfered with though, the particle will collapse to a single state. To guard against that, the researchers turned to superconductors and created cross-shaped qubits they call Xmons. Five of these were then placed next to each other in a linear array, such that each can talk to its neighbor. This provided increased protection from errors appearing in the data.

Even though an error-rate of less than 1% is quite impressive, it will have to fall to below 0.1% to become commercially viable. The physics that enabled the current device can allow for that improvement, but it will be more complex and sensitive, thereby bringing in more issues to address.